Building a great product worthy of conversation is generally thought to be the product manager’s job. My partner, Marty, writes extensively on how. But if you’re in product marketing, you should contribute as well.

Even though we all know a great product is the foundation of evangelism, it’s easy to forget the responsibility of getting there is shared. Many companies are guilty of “product” guys figuring the product out, then handing it over to “marketing” to tell the world about it. Part of a product marketer’s job is to get involved during the product’s planning and ensure it passes these simple tests:

Is this something other people will talk about if we’re not directing the conversation?

Will people like this enough to tell a friend even if they’re not incentivized to do so?

Do we create legitimate opportunities to share value others want?

Take Dropbox. The product guys did an outstanding job of solving a real problem, nailing a killer UE, and focusing on the backend to make the experience as simple and seamless as possible. A quick scan of any thread about Dropbox’s popularity confirms:

Make it just work + Make it dead simple = Product Love

But here’s how Dropbox also passes the above three tests.

(1) Even people not in technology have heard of Dropbox—whether or not they use it—because their tech savvy friends fearlessly recommend it. Dropbox isn’t controlling all these conversations. They’re happening organically because excited fans find new reasons to tell others about Dropbox because it solves real problems, is easy, and works well.

(2) Dropbox’s word-of-mouth marketing is often cited as a key to its success. Although their engineered virality was brilliant, it misses that people refer clients, parents and friends to Dropbox regardless of whether or not they benefit from it. AppStore ratings are another great example of this—ratings influence conversion, yet people write them despite no reward.

(3) Too often, the product solution to marketing is adding a ‘share’ button, social media integration, or enabling referrals. None of this works without something people genuinely value and are motivated to share. Think about the stories you want your customers to tell in a review. What makes them wildly enthusiastic? What makes someone act because of what they read?

It is not “data stored in the Cloud” or “fast cross-platform performance.” What matters—as proven by Dropbox, Pandora, Craig’s List, and the iPad—is when something is as easy and works as well or better than we hope. It surprises and delights. This is the promise of all technology but rarely achieved. When a product actually delivers, people talk about it.

That said, even if you have a great product, encouraging authentic dialog—the key to publicity that doesn’t feel spammy—is work. Be realistic. Make yourself relevant to other peoples’ agendas. When Friendster, the online service that originated social networking, had its initial exponential growth, its founding engineer did all its PR. He sent tech writers his week-over-week growth. At the time, no one had seen anything like it before, so it was a new trend those writers could report on.

Product marketing must be managed on many fronts: search-engines, app stores, social media, web presence, pundits, the blogosphere, or a salesforce. There is no silver bullet. The right mix for any given company is different based on goals, target audience, stage of adoption, where and when people hear messaging, context, reviews, and what people click on when they inevitably google. The telltale sign you don’t have the mix or product right is when your marketing effect is only directly proportional to how much you spend.

The point is: if you want great marketing, make sure you’re starting with a great product. It’s key to the enthusiastic evangelism every product needs. And that is not just the product guy’s job.